Keoman

iTrader: (3)

After completely overhauling the rear end, I get it on the road three days ago and its make a slight whining noise. So I figure I must have done something wrong, tore everything apart and checked backlash/gear pattern/bearing preload... the works. Everything was within specs. The stupid thing that I forgot to do the first time was replace the pinion bearing races (I drove no more than 2 miles on the old ones before i parked it and tore it apart), so I went and got new ones tonight and finally got everything torqued down and put back together only to pull out onto the road and hear that it’s whining even worse this time.
After reading quite a bit, I came across a lot of stuff about whiny rear ends; most of what I can tell is the bearing preload not being set right. I have also heard that the GM addative is very important to stop the noise. However I also noticed this.

Quote:

Originally Posted by big gear head

As far as I know all 9 bolt 3.70 gears make the same noise. Some places will tell you this before you place your order. All I can tell you is to get a louder exhaust or better sterio.

So my question is, how much whining is too much? The whine is a persistent coast (deceleration)/constant throttle situation. I swapped out the series 2 carrier with the stock 2.77 gears and put in 3.70's that i found on ebay for a good price.

Any expert opinions?

Keoman

iTrader: (3)

Alright, just a little update.
I went out this morning and got ambitious and separated the drive shaft from the yoke and tightened it to 130 Ft/lbs. There was some slack that had worked its way into the nut but not much. I was able to turn it a little less than a quarter turn. I havnt put any loctite on it yet because I really want to get rid of the noise and THEN finalize everything.
Anyways, got it out and drove around the block and the noise continues. Its probably around 30 MPH on the coast and constant speed (enough gas to keep the car moving at the same speed) that it starts whining. If I had to describe the noise exactly, my best choice would be almost like how a low tire sounds driving down the freeway. You know, that wao wao wao wao.. (its not the tires, I checked the pressure twice heh..)

Anyways, I am at a loss. I thought I did everything correct but obviously something is amiss.

Oh BTW,
Backlash: .007
Bearing preload (as of right now): 130ft/lbs yoke nut torque (not sure how many in/lbs on the bearings)
When we installed the shims on the side of the carrier, the last shim wasnt all that hard to get in. What i mean is with a little force, you could ge tit in with your fingers. Im not sure how "snug" its supposed to fit in there. Is there a rule of thumb there?

sofakingdom

iTrader: (1)

Torque on the nut is ENTIRELY irrelevant. Doesn't matter in the slightest.

All that REALLY matters in that area, is the preload on the bearings. How many inch-lbs did you leave it set to? Should have been something around 20-25 in-lbs.

Yes that is WAY WAY WAY too loose for the carrier shims. That could be The Problem, right there. The carrier bearings are supposed to have preload, too. I usually try to get AT LEAST .010" of preload on them (housing space is .010" NARROWER than the bearings, requiring a force fit), preferably as much as .020". If you can put shims in by hands, that thing is just SLOPPY loose.

That is too little backlash IMO. Gears get HOT when operating, and hot things GROW. When the gears grow, backlash disappears. If enough disappears, the gears try to occupy the same space; and in this universe, that isn't allowed. Bad things happen when they try. .001" too little backlash = DESTRUCTION; .005" too much backlash = you can just barely tell it's there, if you know what you're looking for and pay CLOSE attention. Which would you prefer?

I shoot for around .010" - .012".

Keoman

iTrader: (3)

Thank you very much for your response. I didn't know about a number of things you mentioned.
First: I have a (1) .010" shim currently. If I stick the shim on the passenger side of the carrier, tightening the preload, will it move the backlash number at all? Logic tells me no because it would have to crush metal in order to move the carrier over against the existing shims. However, I am also wondering if the shim will take up any slack in the carrier and the bearings and slide it over just enough to give me .003/.004" more backlash.
We did try it once already in a different shim position but I personally thought that it made things too tight. (but what do I know) it made the carrier a bit hard to spin around with your hand after everything was installed, including the pinion seal, but maybe it is normal.
Second: the preload before I went and moved the nut in a bit this morning was at approximately 14 in/lbs. So I'm sure it's somewhere in the ball park of 25 or so now, I moved it probably an eighth turn past my mark in the nut.
Sofakingdom, do you know any good remedies for acquiring a .005" shim without buying a shim pack?

Thanks again for your help.

sofakingdom

iTrader: (1)

Backlash doesn't change 1-to-1 with the shim; i.e. changing the shim .005" won't change the backlash .005". Probably more like, the backlash changes .003" to .004" for every .001" of shim change. But, if you just add .010" of shim to one side, that will move the carrier by .005", since adding preload to the bearings compresses them equally (more or less).

What you should do next, depends on what you have, and what you've already done.

What gears did you use? What shim did you put behind the pinion head bearing? How did you determine that? What shim was in that place, stock? What happened to the rest of the carrier shims in your install kit?

Keoman

iTrader: (3)

Ok.
I bought this carrier and pinion assembly already rebuild for a lot less than it would have cost me to do it piece by piece. In addition, it came with the 3.70 gears (wasnt planning on quite going to 3.70 but I did want the 3series carrier so it was a nice combo)
The thing came pretty much as a pre-assembled kit with specified shims for each side that the dude had already set up. Anyways, I knew it wasn't going to fit exactly but I thought I'd try what he gave me and see where I stood.
The kit only came with the "pre shimmed" shims so I have only the stock ones from the last carrier and the new ones he sent me; about 5 in total.
As far as the pinion shim, the stock shim is still in there. (probably the problem as I just had an epiphany that it probably needs changed as well. I'm in the process right now of painting the gears and seeing exactly what the pattern looks like (as the current shims lay, without the .010" shim in the passenger side). If the pattern looks good, I was going to pop that .010" shim in there and see how things set up.
I hope that helps you help me.
I'll take a picture of the pattern as best I can and post it up.
Thanks.
Keo

Keoman

iTrader: (3)

Oh, btw, both the pinion and the ring gears have 611 engraved in them. The pinion is engraved with 2125" also. The ring is stamped 10090 GM9 370 10x37.

sofakingdom

iTrader: (1)

OK... that explains why it doesn't work.

The shims are part of the housing, not the moving parts. What you are shimming when you put the thing together, is not the gears or the carrier; it's THE HOUSING. The machine work on the moving parts is probably 20 times as precise as that on the housing. IOW, about 99% of the time, you can take ANY gears (well, almost, there are exceptions, but let's leave that aside for the moment) and ANY carrier and ANY bearings (as long as they're not worn), and swap them into ANY housing using the same shims that were already there (as long as they're not worn also), and it will work. BUT.... put ANY moving parts from ANYWHERE into ANY OTHER housing, and since the housing will be DIFFERENT, it won't be anywhere near correct alignment, without selecting different shims.

Imagine it like this: you've got a set of PERFECTLY aligned moving parts jus chillin out in space somewhere, in PERFECT relationship with each other. Now, you choose shims that allow you to hang a random housing (and yes, they're pretty darn random) PERFECTLY around them without disturbing their PERFECT alignment.

So: as it stands now, your gears are all set up perfect (or maybe not...) for SOME OTHER housing, meaning, they're GUARANTEED to be TOTALLY WRONG for YOUR housing.

Make sense so far?

So: go find your original pinion, and measure the shim behind the bearing. Or, if it's like some 9-bolts, the shim may have been in the bearing bore in the housing, behind the head bearing outer race. Whichever arrangement you have, go get that shim, and put it back where it was, behind your new gear and bearings. Tighten the nut to get 20-25 ft-lbs of preload on the bearings.

Then, get your original carrier shims, and put them back into your housing, with the new carrier & bearings. Or even better, measure your old shims, and create shim packs out of the ones that came with your new stuff, that are the same thickness. Stack the thin shims between pairs of the thick ones. Then put it back together like that. Check the backlash and try to get it to about .010", with about .010" of preload (press fit into the case) on the carrier bearings. I do that myself with 2 giant C-clips, I don't have a "case spreader". If the preload is off, add or subtract shims EQUALLY from both sides to get it there. If the backlash is out of tolerance, move shim thickness from one side to the other, in a ratio of about .001" of shim for every .003" of preload you want to add or take out. You measure backlash at the outer edge of a ring gear tooth, by rotating the carrier by hand from one side of the clearance to the other with a dial indicator on it.

Then test-drive it.

Odds are, it'll be REAL close, AND quiet.

If you don't have the shims to do that with, you'll have to buy a shim pack. Not much way around it.

Keoman

iTrader: (3)

Makes perfect sense, thank you for the explanation.
You said to put the stock pinion depth shim back in, but the thing is, it is in there right now. (It sits underneath the inner bearing race BTW, not between the gear and the bearing.) I just got done checking the gear pattern and its atrocious. Totally wrong. From what I can decipher, these marks indicate that the shim needs to be thinner. Im not exactly sure which shim is in there now, but im planning on pulling it out tonight and getting out the mic.
About the stock carrier shims, I tried to put them back in but together, they leave enough slop between the carrier and the housing to stick the tip of a flat headed screw driver in there and wiggle it around. I found it kind of odd that its SO much smaller than the stock 2 series. If i had to guess, i'd say it left at least an eighth of an inch play with the stock carrier shims. Unless im crazy and putting the shims in wrong (which im not sure that you can) its not even close.

Anyways, here is the pattern i pulled off tonight.





Any other information that i can provide that would help, please ask and ill do my best.

Oh, and just to make sure, you meant in/lbs of preload on that pinion bearing right?

sofakingdom

iTrader: (1)

Yes, sorry about that, in-lbs.

Yeah you've got a mess on your hands there. I wonder what kind of gears those are.

It looks to me like it needs more pinion shim, since the pattern is too close to the center of the ring; and there's too much backlash.

Shim pack time I'm afraid...

Keoman

iTrader: (3)

Turned out pretty good. Just got everything put back together and waiting for help to get it under the car again. Ok so what I ended up with in the end.
First: I dissasembled everything and got that shim out from under the race. Best i could tell, .015" shim. I decided that the pattern was so far off that removing the shim completly might actually do the job, so I did. Ended up with a very nice pattern which made my whole day. (pics below)
Second: by removing the shim and setting the pinion deeper in the housing, it actually increased my backlash by about .006" setting it to a final value of .012". However, since my carrier was entirly too loose, like sofakingdom said, i put the .010" carrier shim in the driver side and it set the backlash back at .008". (.010" shim on one side moves backlash about .004") So now I have a very acceptable gear pattern and am over the .006" backlash that i started with.
So my final values ended like so:
Pinion Preload: 22 in/lbs
Backlash: .008"
Gear pattern: see pics
I am much more comfortable about the setup now. You know, taking the rear end out of the car 3 times on my first ever rear end setup isnt too bad i guess... heh. Better not speak too soon though..

Pinion Shim: .015" (removed completly)


Stock carrier shims from the 2 series carrier i had before, Notice the massive Un-shimmed space on the right side.


Gear Pattern. Pretty much as good as its going to get. Remember, there is absolutly no shim in there right now so moving the pattern more to the middle of the gear would require either machining out the housing or machining the bearing race to a thinner dimension to compensate. Given the two i'd probably take a little off the race first and see where that gets me.






Thank you for the help and info. I hope this works just peachy now. HID system came today, so after the rear end is in i finally get to finish my projector retrofit and install it!
Keo

sofakingdom

iTrader: (1)

That looks AHELLUVALOT better.

Hope it works out!!

Keoman

iTrader: (3)

Ok sooo heres where I'm at!
With the new settings I went ahead and installed it this morning and drove him around a bit. SOUNDS AMAZING! The whine completly dissapeared, at least to the 40 or so MPH that i took it up to. Drove it around for about 15 minutes and came back. What a difference!
Definatly helped / fixed the problem. Now that its in, time to break it in right? Any advice or suggestions? I have read a bunch of stuff, everyone seems to have their own way of doing it. Everything from, 15 min of drive time and let cool for 30 min... after 100 miles replace the gear oil... after 500 miles replace the gear oil... no freeway's, no speeds above 50 MPH for the first 100 miles.. tons of stuff.
Anyone have what they see as the right way to break in a readend?

74Novaguy

Ive always been told "drive it like you stole it" then do the first gear oil change after 500 miles...

sofakingdom

iTrader: (1)

For break-in on NEW gears, drive it at a moderate speed, varying up and down, for 10-15 minutes or so; enough to heat them all the way up. Don't beat on them during this time, but don't baby them, and don't drive at a constant speed or go over about 55 or 60 mph. Park it, let them cool completely, then they're ready to go.

Used gears need nothing.

Never hurts to change the fluid. Used ones probably won't require it. If your magnet in the case was clean, even new ones probably don't need it; brand-new cars for example, don't EVER get a gear lube change early in their life, and you might be surprised, for that matter, to go through junkyards, and see how many have reached the end of their productive, 250,000 mile service life with the factory fill fluid in them. Not that that's good; but should put the "need" aspect into a better perspective.

Keoman

iTrader: (3)

Great, thanks for the info. I'll probably baby them a little longer than 15 minutes of driving just to make myself feel better. I'll change the oil after 500 miles anyways, nobody ever got into trouble changing fluids in their car too often. Right now I have some mobile 1 non-synthetic oil in there, is it against the rules to run full synthetic? Any need for the gm additive or ford friction modifier?
Keo

85 ZXX

iTrader: (1)

Twin Turbo has a few 9 bolt cars and he said to use regular hypoid gear oil, the highest you can get.90-140. I think the 140 will quiet the whine down some. Look him up on TGO...he knows alot about this.

Keoman

iTrader: (3)

For sure, thanks.

85 ZXX

iTrader: (1)

Its Twin_Turbo, He is on my friends list in my public profile...He has done some exceptional work on his cars....Check out his post and photos.

Keoman

iTrader: (3)

With reguard to my thread title, I would like to add my .
The gears are strange. In very specific senarios they will wine however about 95% of the time they are silent. For EX: decelerating pas 60-55 they will start to make some noise and below 55 it dissapears. So they whine a little... oh well.
Just didnt want to leave the thread without giving my Input.

85 ZXX

iTrader: (1)

Keo,

I finally got mine installed...I did a bunch of other upgrades too. Check out my signature links for recent pics.

Yesterday I got (Lazarus) off the jackstands and will get a AutoTransport Trailer from U-Haul and tow to the alignment shop.

The 3:27 9bolt should work nice with the 150hp NOS kit that I ordered.

Keoman

iTrader: (3)

Looks great Sox..
Im coveting your brakes. I was out at the JY a couple weeks agao and found a 99 Z28 that had been totaled on the drivers front. Only found the passenger Caliper. Picked it up for dirt cheap. Just gotta find a Drivers now. I can cut and drill the rotors myself, its just the relocation brackets that I would have to have made.
Great work.

TPI-Formula350-

good write up. I brought a rebuild 9 bolt off craigslist last year. The guy had pics of the build and receipts for the parts(friction cones,bearings ring pinion ect) from 9 bolt.com. It looks nice painted in POR15, nice TA Performance cover ect ect. I'm really not happy with it, he didnt shim the friction cones correctly. I did the break away test and it failed <35 ft.lbs. and goes 1 legged under hard accel. It also whines on decel but not under accel. I just ordered a friction cone shim kit from 9 bolt.com. I'm hoping to get posi when I need it after installing the shim kit. I printed out the "servicing 9-bolt(BW) limited slip units" from the home page tech section. So maybe between this thread and the friction cone shim kit I can get posi when I need it and quite it up a little.

Keoman

iTrader: (3)

Yeah definatly need to shim the posi a bit if it's not working at all, make sure you check your cones real good for wear and clearance in the housing windows so you don't have happen what happened in my "Evil Noises" thread.
I am going to be rebuilding the 3.70 with 3.23's here in about a month.
Let me know if I can help.

TPI-Formula350-

Thanks

trevor1010

HEY MY CAR IS MAKING A WHINNING NOISE DURING DECELERATION. IVE HAD TWO DIFFERENT SHOPS LOOK AT IT AND THEY'VE DONE ALL THEY COULD. DO YOU THINK WHAT YOU DONE MAY FIX MY ISSUE. IF SO HOW COULD I TRY IT MYSELF. I KNOW NOTHING ABOUT REAR ENDS I JUST HATE TO TAKE IT TO ANOTHER SHOP